<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script type="text/javascript" src="../js/js_induction.js"></script>

</head>
<body>
<input type="button" value="新窗口打开网站" onclick="openWindow()"/>
<input type="button" value="打开网站" onclick="openn()"/>
<input type="text"/>
</body>
<script type="text/javascript">
    var i = document.querySelectorAll('input[type="button"]');
    var j = document.querySelectorAll("button");
    document.write(j.length);
    console.log(i.length);
</script>
</html>